Digital maps are now widely used for a variety of purposes, including monitoring traffic and road conditions, planning routes, locating landmarks such as retail establishments, parks, etc., and/or navigation of an autonomous or semi-autonomous vehicle along a route according to information on the digital map. Road signs can convey useful information about a planned or potential vehicle route, e.g., speed limits, stop signs, lane shifts, etc. However, digital maps at present are often out-of-date or inaccurate, e.g., because signs have not been properly included on the digital maps, signs have been posted or taken down since a last update, etc., or the potential vehicle route has not been mapped to provide a digital map.